Today's wireless communication systems provide a broad range of services to both individual communication units and groups of communication units while they move about. These services include cellular telephony, group dispatch, and packet data, to name just a few. A typical example of such a system 100 is illustrated in FIG. 1. The configuration shown in FIG. 1 is typical in wireless communications systems such as Global System for Mobile Communications (GSM), Advanced Mobile Phone Service (AMPS), Terrestrial Trunked Radio (TETRA), “IDEN”, and “SMARTZONE” systems. As shown, a central switch 101 provides connections between cell sites 104–107.
A plurality of communication units 110–115 (e.g., mobile or portable radios, cellular telephones, personal digital assistants (PDAs)) wirelessly communicate with the sites 104–107 and each other, and are often logically divided into various subgroups or talk groups. In such a system, the call processing management and switching functionality are generally contained within the same physical unit, i.e., the central switch 101. The sites 104–107 are connected to the central switch 101 through dedicated or on-demand links and intermediate processors 102–103 in what is often called a “star” configuration. Some very large systems use a hierarchy of such “stars” where intervening concentrators group the links from multiple cell sites and do some lower level processing on them before passing them up to the central switch.
Next-generation wireless systems propose to employ multicast addressing protocols, such as multicast Internet Protocol (IP) for providing group or dispatch call services. Examples of IP Multicast communication systems include the referenced U.S. patent application Ser. No. 09/283,121, now issued as U.S. Pat. No. 6,141,347; and U.S. patent application Ser. No. 09/464,269, titled “Methods for Implementing a Talkgroup Call in a Multicast IP Network,” each of which is assigned to Motorola, Inc. and incorporated herein by reference in its entirety.
Generally, IP multicasting protocols are considered to be more efficient and less costly than traditional circuit-switched networks. The multicast IP network defines a distributed, rather than centralized, connection and mobility processing environment where there is no centralized location register (VLR/HLR). Rather, mobility information is inherent to the packet network as communication units register or de-register individual or group affiliations with cells, and the cells join or leave multicast IP addresses to participate in traffic for the communication units. The benefits of a distributed connection and mobility processing environment include fully localized resource management, fully distributed mobility management and easy network scalability.
Heretofore, distributed connection and mobility processing networks such as multicast IP networks have been used for one-to-many communications (e.g., talkgroup calls) but not for one-to-one communications, specifically 2-party calls. It would be desirable to extend the benefits of distributed connection and mobility processing, using IP multicast techniques, to support 2-party calls. The present invention is directed to satisfying this need.